The invention relates to a method for controlling an aircraft in the form of a multicopter, which multicopter comprises several, preferably redundant rotors arranged in a common rotor plane, in order to generate lift, on the one hand, and propulsion, on the other hand, by inclining at least one rotor plane, with the adjustment of the position and the control of the multicopter occurring by changing the rotor speeds depending on pilot control instructions.
Additionally, the invention relates to a control system for an aircraft in the form of a multicopter, which multicopter comprises several redundant rotors, preferably arranged in a common rotor plane, in order to generate lift, on the one side, and also propulsion, on the other side, by inclining at least one rotor plane, with the adjustment of the position and the control of the multicopter occurring by changing the rotor speeds depending on pilot control instructions.
Additionally, the invention relates to an aircraft in the form of a multicopter, which multicopter comprises several redundant rotors, preferably arranged in a common rotor plane, including respectively at least one electric motor and one propeller, in order to generate lift, on the one side, and also propulsion, on the other side, by inclining at least one rotor plane in the space, with the adjustment of the position and the control of the multicopter occurring by changing the rotor speeds depending on pilot control instructions.
An aircraft is known from DE 20 2012 001 750 U1 in the form of a vertically starting and landing multicopter, which aircraft can be controlled via a generic method and/or shows a respective generic control system.
A “multicopter” is considered here and in the following an aircraft, which uses several rotors or propellers preferably arranged in a common plane and acting vertically downwards, in order to generate lift and also propulsion, by inclining particularly one rotor plane. A multicopter is considered a rotor aircraft and thus can land and take-off vertically.
Unlike conventional helicopters, multicopters use no mechanical control elements. The rotors and/or propellers exhibit a fixed pitch and are not adjustable, which lowers the production costs and reduces the need for maintenance.
Any changes of the lift occur exclusively by increasing or reducing (changing) the motor speeds at the electric motors used for driving the propellers. Here and in the following “rotor” represents the combination of electric motor and propeller, while “propeller” only refers to the actual airscrew itself.
In a multicopter the rotors move in opposite directions, one half in the clockwise direction, the other half in the counter-clockwise direction. This way the torque about the vertical axis, developing by the propellers upon the support frame of the multicopter, compensate each other when the totals of the forces of the clockwise and/or the counter-clockwise spinning propellers are equivalent.
A rotation of the multicopter about the vertical axis (yaw axis) can be achieved by different rotations of the clockwise and counter-clockwise spinning rotors. For an incline about the pitch axis (pitching) the rotary speeds of the frontal and the rear rotors are varied, for an incline about the longitudinal axis (rolling) the speeds of the rotors located at the left and at the right. By the incline, here propulsion is possible not only in the vertical direction but also in the horizontal one, thus allowing a motion in any arbitrary direction.
Multicopters are aerodynamically instable. A stable flight behavior can only be achieved by a permanent adjustment of the rotary speeds of the individual rotors.
The pilot of the multicopter controls not the rotary speed of the individual motors, but only sets parameters, such as direction of flight, speed, rate of incline or decline, etc. This can occur for example by joysticks, switches, and similar control elements.
In a multicopter used for transporting persons it is mandatory that the entire control operates with utmost reliability. The failure of individual components, e.g., individual sensors, control processors, or motors, may not lead to any risks for maneuverability or to a crash of the multicopter.
Additionally, several unmanned multicopters are known from prior art, for example for model aviation or used as monitoring drones, which typically exhibit a central control, which determines the target rotary speeds for all rotors and forwards them to the respective motor controllers. Any failure of this central adjustment leads quasi mandatorily to a loss of control of the multicopter and to its crash.
In manned aviation it is common to provide critical components in redundant numbers, e.g., in duplicate or triplicate. In this context then mandatorily a superordinate decision maker is provided, the so-called “voter” or “arbiter”, which monitors and decides, which of the critical components still operate correctly. This decision maker may represent the pilot him/herself, who for example decides in the event of deviations between the statements of various instruments based on criteria “majority” and “plausibility” and perhaps shuts off or ignores certain components. The decision maker may also be embodied in the form of an electronic unit, which compares the output (the output signals) of the redundant components and renders a decision according to the majority principle.
However, an electronic “voter” itself represents a “single point of failure”, because due to its purpose it must be able to ignore or overwrite the output of certain components. Accordingly, in case of a faulty behavior of the “voter” it may occur that correct control pulses are suppressed and instead faulty control pulses are forwarded. Additionally it may occur that the “voter” itself generates faulty pulses, which may endanger the safety of the flight behavior.
Even in case of a triplicate redundancy of the individual control components and a theoretically considered infallible “voter”, a multicopter could crash in case of a failure of only two control components. Accordingly in such a solution extremely high requirements are set for the reliability of the components involved, which would lead to respectively increased production, maintenance, and cost expenses.